Anderson and D’Alonzo classified odontoid fractures as Type I, II, or III. The classification was modified by Grauer. According to Grauer classification, the dens fractures were Type IIA in 3 cases, Type IIB in 3 cases, and Type IIC in 2 cases in this series. Single Type II fracture can be treated by external fixation (IIA), anterior screw (IIB), and posterior C1-2 fusion (IIC). As to Type II odontoid fracture combined with Hangman fracture, the treatment remains controversial. In this series, all cases were managed with posterior temporary C1-2 pedicle screw fixation. There were a few advantages to using this technique for such cases.
First, posterior internal screw fixation gives immediate direct fixation of the fracture and offers a high rate of fusion without requiring prolonged halo vest immobilization. In 2001, Harms and Melcher described C1 lateral mass and C2 pedicle screws used to achieve posterior atlantoaxial stabilization with polyaxial screw-rod system. Biomechanically, the overall rigidity achieved using this technique is similar to that achieved with transarticular screws. In this series, all patients acquired bone healing at 3 to 9 months after surgeries. We chose pedicle screws instead of lateral mass screws for C1 temporary fixation. C1 pedicle screw has a few advantages than lateral mass screw: pedicle screws have superior resistance to pullout via axial load compared with lateral mass screws in the atlas; C1 pedicle screw does not require extensive dissection to expose the C1 lateral mass for screw placement, this technique decreased occipital neuralgia and blood loss.
Second, posterior temporary C1-2 pedicle screw fixation preserves the normal mobility of C1-2. Traditional bony fusion of C1-2 was canceled to preserve the atlantoaxial rotary function. Guo et al compared clinical results of 22 patients who underwent posterior C1-2 temporary fixation of an odontoid fracture and 21 patients treated with posterior C1-2 fixation and fusion. Significantly better outcomes were observed in the temporary-fixation group for visual analog scale score for neck pain, NDI, and neck stiffness. The outcomes in the temporary-fixation group were superior to those in the fusion group in all dimensions of the 36-Item Short Form Health Survey. There were no significant differences in fracture healing rate and time to fracture healing between the 2 techniques. In our study, the neck disability caused by posterior fixation was obvious. The average NDI (raw score) before and 2 days after instrumentation removal were 10.1 ± 4.0 and 7.1 ± 3.0, respectively. The neck rotary range was obviously limited and decreased to 70.4 ± 6.3°. After the implant was removed, the neck rotary function was immediately improved to 119.6 ± 13.1°. At 1-year follow-up, the neck rotary function and NDI were significantly improved.
Third, posterior temporary C1-2 pedicle screw fixation can be used in some cases which are not suitable for ACSF. Anterior screw was first reported in 1980 by Nakanishi. The reported union rates of surgical treatment ranged from 88% to 100%.[6–8,21] There is a number of advantages including immediate stabilization, less postoperative pain, no requirement for bone graft, and preservation of the normal atlantoaxial rotational movement. However, there are also a few contraindications for anterior fixation. Type IIC dens fracture provides only a small part of the C2 body for anchorage of the screw and the fracture line parallel to the screw trajectory can easily result in anterior displacement of the fragment under compression, and significantly more likely to result in nonanatomical union, nonunion, or fibrous union than posterior oblique and horizontally oriented fractures. Moreover, contraindications of odontoid screws also included fracture comminution, severe cardiothoracic kyphosis, severe osteoporosis, late fractures, and ligament transverse rupture. Posterior temporary C1-2 pedicle screw fixation is an appropriate option for such cases. In this series, 1 Type IIC dens fracture with Hangman fracture was successfully treated by this technique. According to our data (unpublished), bone-healing rate of Type IIC dens fracture was much better than anterior screws (96% vs. 90.6%, P < .05).
There are some shortcomings of posterior temporary C1-2 pedicle screw fixation for 3-part fracture of the axis: The patients need second surgery to remove the instrumentation. After temporary fixation, it eliminates the normal C1-2 rotatory motions, which is responsible for approximately 54.03% of cervical rotary motion according to our data; cervical rotary motion may be affected by temporary fixation even after hardware removal. The patients may need a long time to recover to the normal motions. In this series, the neck rotary motion 2-day after instrumentation removal was only 119.6 ± 13.1°. At 1-year follow-up, the average neck rotary motion was improved to 153.1 ± 9.1°; this technique cannot be used for the treatment of the patients associated with disruption of the disc at C2/3; although all cases in this series were treated successfully, complications of posterior fixation may include blood loss, vertebral artery injury, infection, and others according to the literature. The present study is a retrospective case series study that only included 8 patients, the study design and the small sample size may be a major limitation of the strength of the conclusion. Further researches with large sample size or with the design of prospective randomized control trial may be more convincing for clinical implication.
With regard to the high fracture fusion rates, low complications, and excellent predictable outcomes in patients treated with posterior temporary C1-2 pedicle screw fixation, the technique may be a suitable choice for 3-part fracture of the axis.
Data curation: Suomao Yuan, Bin Wei, Yonghao Tian.
Formal analysis: Suomao Yuan, Bin Wei, Yonghao Tian.
Funding acquisition: Lianlei Wang, Xinyu Liu.
Investigation: Suomao Yuan, Bin Wei, Jun Yan, Wanlong Xu, Lianlei Wang, Xinyu Liu.
Methodology: Suomao Yuan, Bin Wei, Jun Yan, Wanlong Xu, Lianlei Wang, Xinyu Liu.
Resources: Yonghao Tian.
Software: Bin Wei, Yonghao Tian, Jun Yan, Wanlong Xu.
Supervision: Yonghao Tian, Wanlong Xu, Lianlei Wang, Xinyu Liu.
Writing – original draft: Suomao Yuan.
Writing – review & editing: Suomao Yuan, Xinyu Liu.
. Greene KA, Dickman CA, Marciano FF, et al. Acute axis fractures. Analysis of management and outcome in 340 consecutive cases. Spine 1997;22:1843–52.
. Harms J, Melcher RP. Posterior C1-C2 fusion with polyaxial screw and rod fixation. Spine 2001;26:2467–71.
. Govender S, Maharaj JF, Haffajee MR. Fractures of the odontoid process. J Bone Joint Surg Br 2000;82:1143–7.
. Coyne TJ, Fehlings MG, Wallace MC, et al. C1-C2 posterior cervical fusion: long-term evaluation of results and efficacy. Neurosurgery 1995;37:688–92.
. Marcotte P, Dickman CA, Sonntag VK, et al. Posterior atlantoaxial facet screw fixation. J Neurosurg 1993;79:234–7.
. Grob D, Jeanneret B, Aebi M, et al. Atlanto-axial fusion with transarticular screw fixation. J Bone Joint Surg Br 1991;73:972–6.
. Apfelbaum RI, Lonser RR, Veres R, et al. Direct anterior screw fixation for recent and remote odontoid fractures. J Neurosurg 2000;93(suppl):227–36.
. Henry AD, Bohly J, Grosse A. Fixation of odontoid fractures by an anterior screw. J Bone Joint Surg Br 1999;81:472–7.
. Xiangyang M, Jincheng Y, Qingshui Y, et al. The primary outcome of posterior nonfusion screw-rod fixation for preserving the atlantoaxial rotary function due to fresh type II odontoid fracture
. Chinese J Spine Spinal Cord 2013;23:411–5.
. Han B, Li F, Chen G, et al. Motion preservation in type II odontoid fractures using temporary pedicle screw fixation: a preliminary study. Eur Spine J 2015;24:686–93.
. Daum W, Archer CR. Fracture of the odontoid associated with pedicle fracture of the axis: a previously undescribed entity. J Trauma 1977;17:381–6.
. Korres DS, Papagelopoulos PJ, Mavrogenis AF, et al. Multiple fractures of the axis. Orthopedics 2004;27:1096–9.
. Koller H, Assuncao A, Kammermeier V, et al. Simultaneous anterior arthrodesis C2-3 and anterior odontoid screw fixation for stabilization of a 4-part fracture of the axis—a technical description. J Spinal Disord Tech 2006;19:362–7.
. Blondel B, Metellus P, Fuentes S, et al. Single anterior procedure for stabilization of a three-part fracture of the axis (odontoid dens and Hangman fracture
): case report. Spine 2009;34:E255–7.
. Shinbo J, Sameda H, Ikenoue S, et al. Simultaneous anterior and posterior screw fixations confined to the axis for stabilization of a 3-part fracture
of the axis (odontoid, dens, and Hangman fractures): report of 2 cases. J Neurosurg Spine 2014;20:265–9.
. Anderson LD, D’Alonzo RT. Fractures of the odontoid process of the axis. J Bone Joint Surg Am 1974;56:1663–74.
. Grauer JN, Shafi B, Hilibrand AS, et al. Proposal of a modified, treatment-oriented classification of odontoid fractures. Spine J 2005;5:123–9.
. Zarro CM, Ludwig SC, Hsieh AH, et al. Biomechanical comparison of the pullout strengths of C1 lateral mass screws and C1 posterior arch screws. Spine J 2013;13:1892–6.
. Pan J, Li L, Qian L, et al. C1 lateral mass screw insertion with protection of C1-C2 venous sinus: technical note and review of the literature. Spine 2010;35:E1133–6.
. Guo Q, Deng Y, Wang J, et al. Comparison of clinical outcomes of posterior C1-C2 temporary fixation
without fusion and C1-C2 fusion for fresh odontoid fractures. Neurosurgery 2016;78:77–83.
. Song GS, Theodore N, Dickman CA, et al. Unilateral posterior atlantoaxial transarticular screw fixation. J Neurosurg 1997;87:851–5.
. Denaro V, Papalia R, Di Martino A, et al. The best surgical treatment for type II fractures of the dens is still controversial. Clin Orthop Relat Res 2011;469:742–50.
. Joaquim AF, Patel AA. Surgical treatment of type II odontoid fractures: anterior odontoid screw fixation or posterior cervical instrumented fusion? Neurosurg Focus 2015;38:E11.
Keywords:Copyright © 2018 The Authors. Published by Wolters Kluwer Health, Inc. All rights reserved.
Hangman fracture; odontoid fracture; temporary fixation; 3-part fracture